In this project, we are attempting to study cell surface antigens that are specific to tumors. For this purpose, we are producing hybridomas from mice that have been immunized with human leukemia and lymphoma cells. The objective is to find antibodies that are useful in categorizing and diagnosing human lymphoid malignancies. Techniques of flow cytometry of cells in suspension and immunoperoxidase of frozen tissue sections are being employed. A number of monoclonal antibodies are being made available for clinical application. During the past year, we have identified prognostic groups of patients with diffuse histiocytic lymphoma and have defined T-cell ALL with a single monoclonal antibody. (AG)